Addition and subtraction of several algebraic expressions are usually enclosed in brackets and then connected by addition and subtraction signs. The general steps of algebraic expression addition and subtraction are:

(1) If you encounter brackets, remove the brackets according to the rule of removing brackets: there is a "ten" in front of the brackets, and remove the brackets and the "+"in front. Everything in brackets has the same symbol, and the "one" comes before the brackets. Remove the brackets and the preceding "one". Everything in brackets has the same symbol.

(2) Merging similar items: adding the coefficients of similar items, and taking the result as the coefficient. Letters and the index of letters remain unchanged.